The overall goal of this pilot study is to confirm preliminary data which indicates the following: * Complete hysterectomy (CH) at either 21 days (CH-21 days) or 60 days (CH-60 days) significantly reduces RV and LV size at either 4 months or 6 months of age. * CH-21 days and CH-60 days significantly alters contractile mechanics in papillary muscles isolated from the posterior wall of the LV. * Hormone replacement therapy (HRT) of extrogen (2 mg/kg/day), administered via Alzet mini-pumps significantly reduces alterations in RV and LV size as well as contractile deficiencies in LV papillary muscles following CH. In this pilot study experiments will be conducted in order to determine: * The validity of preliminary data dealing with alterations in RV and LV size following CH. * The validity of data demonstrating alterations in LV papillary muscle contractile function following CH. * The minimum threshold (delay) between CH and HRT that results in altered cardiac size and/or contractile function. * The effect, if any, upon adrenergic receptor density following CH. * The effect, if any, of HRT upon adrenergic receptor density following CH.